Budapesti Muszaki Egyetem

Gyorgy Danko

Imre Szabo

Gyorgy Kulin

Istvan Czifka

Zsolt I Vitez

A process for the simultaneous, in-situ determination of thermophysical properties, primarily for determination of the thermal conductivity and thermal diffusivity, according to which in a certain volume of the material to be tested a temperature field varying with time is brought about by perturbation due to heating and this temperature field is measured, then certain properties are determined by calculation from the obtained temperature data and the known heating power input spherical isotherms are formed in the material to be tested in a way, that temperature change of at least one degree Celsius is brought about at the measuring points which are arranged along a straight line passing through the heat source and intersecting the isotherms along their diameter, and a measuring probe formed as a rod-type body made of poor heat conductive material having a heating element and measuring points, wherein the heating element is formed as a point-like heat source.

Process and apparatus for the determination of thermo-physical properties

A method for the determination of the heat transfer coefficient on a heat transferring surface, including the steps of arranging a layer for measuring the surface temperature and heat flux on the heat transferring surface so that the layer can change the original temperature and heat flux to a negligible extent only, providing for the slight and properly slow changeability of the surface heat flux density within a cycle time which is by several orders of magnitude longer than the time constants of the heat flux measuring layer and of the heat transferring boundary layer, by using a supplementary heating element and performing a practically unlimited number of measuring cycles, using the steps of deflecting the surface heat flux density and temperature relative to the condition in which no measurement takes place. The time-functions of the changes of the surface temperature .DELTA.T and of the surface heat flux density .DELTA.q are determined, and the heat transfer coefficient is defined as the approximate limit value H of the quotients .DELTA.q/.DELTA.T corresponding to the zero surface heat flux density or temperature deflection.

Growing community of inventors

Budapest, Hungary

Gyorgy Danko